High-frequency electromagnetic properties of compositionally graded FeCoB-SiO2 granular films deposited on flexible substrates

Abstract

In order to break through the conductive percolation threshold limitation of the conventional granular films to increase resistivity (ρ), while keeping large complex permeability (μ̃), a series of compositionally graded FeCoB-SiO2 granular films with different multilayer structures were deposited on flexible substrates. The high-frequency electromagnetic properties were investigated. The experimental results showed that the compositionally graded granular films had obvious in-plane uniaxial magnetic anisotropy and the coercivity in the easy axis (Hce) was as low as 3.97 Oe. Both the ρ (∼15.4 mΩ·cm) and μ̃ (μi'=276.3 and μ″max=441.4) of the compositionally graded FeCoB-SiO2 granular films were simultaneously higher than those of the conventional FeCoB-SiO2 granular films. Two resonance peaks of complex permeability spectrum were also observed.